Although routinely monitored by ground based air quality networks, the particulate
matter distribution could be eventually better described with remote sensing techniques.
However, valid relationships between ground level and columnar ground based quantities
should be known beforehand. In this study we have performed a comparison between
particulate matter measurements at ground level at different cut sizes (10, 2.5 and 1.0 mm),
and the aerosol optical depth obtained by means of a ground based sunphotometer during
a multiinstrumental field campaign held in El Arenosillo (Huelva, Spain) from 28 June to
4 July 2006. All the PM fractions were very well correlated with AOD with correlation
coefficients that ranged from 0.71 to 0.81 for PM10, PM2.5 and PM1. Furthermore, the
influence of the mixing layer height in the correlations was explored. The improvement in
the correlation when the vertical distribution is taken into account was significant for days
with a homogeneous mixing layer. Moreover, the chemical analysis of the individual size
fractions allowed us to study the origin of the particulate matter. Secondary components
were the most abundant and also well correlated in the three size fractions; but for PM10
fraction, chemical species related to marine origin were best correlated. Finally, we obtained
a relationship between MODIS L3 AOD from collection 5.1 and the three PM cut sizes.
In spite of being a relatively clean environment, all the techniques were able to capture
similar day to day variations during this field campaign.